Saturday, November 15, 2008

The Research Project

The Dry Valleys are a cold desert. Water in its liquid and frozen form is very rare. Streams only occur as glacial melt water streams. A few lakes exist at low elevation of the Dry Valleys but at higher elevations they disappear. The entire Dry Valleys are underlain by permafrost. Permafrost is ground that has temperatures below 0° C for the entire year. This frozen ground is often a mixture of sediment and ice and is called ice cemented permafrost. During winter when soil temperature drop below -40 to -60°C this ice shrinks and cracks form on the surface. Such cracks are arranged in polygonal pattern. Below is a picture that shows such pattern, the polygons have a diameter of about 20 to 30 m.
Such patterns only form because ice is present in the ground that contracts at cold temperatures. Therefore, everywhere were we are observing polygons at the surface we know that ground ice is present at depth. Our research is tight connected to the ground ice. Since very little snow falls during the year and relative humidity often drops below 10%, it is very surprising that ice is stable in the ground. We want to understand why ice is pervasive in the Dry Valleys (we know this because we can see the polygons at the surface when we fly with the Helicopter). Understanding the nature of ground ice has multiple applications. One is its relation to Mars. Researcher observed the same polygonal pattern on Mars and they know from the Dry Valleys that this indicates ground ice. Understanding the nature of ice in the Dry Valleys will also help understanding if there is ice on Mars and how it may be formed. Actually the Dry Valleys are a lot like Mars (or vise versa) and are called the best Mars analogue on Earth. Secondly, if ice is present it may indicate that liquid water is present which is essential for life. Liquid water could be one mechanism to fill the ground with ice. If we understand this mechanism in Antarctica we may also be able to better understand and prdict the occurrence and persistence of water/ice on Mars.
So here we are and start our investigation. During this field season we will take 10-20 m log cores out of the polygon. The cores will be shipped back home and analyzed for their composition. We hope this will tell us something about the history of the ice.

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